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In residential applications, an air-to-water CO 2 heat pump is used in combination with a domestic hot water storage tank, and the performance of this system is affected significantly not only by instantaneous ambient air and city water temperatures but also by hourly changes of domestic hot water consumption and temperature distribution in the storage tank. In this paper, the performance...
The numerical simulations of simultaneous heat and mass transfer process in the counter-flow spray saturator and humid air turbine cycle are carried out in this work, according to the experimental conditions and actual size of a prototype saturator. This humidifying process involves two-phase flow of air and water droplets, also including interaction, breakup and collision of water droplets. Eulerian...
Air-to-water heat pumps using CO 2 as a natural refrigerant have been developed and commercialized. They are expected to contribute to energy saving in residential hot water supply. The objective of the research is to analyze the performance of a water heating system composed of a CO 2 heat pump and a hot water storage tank by numerical simulation. In this paper, the system performance...
Utilization of riverbank filtrate water for heating and cooling of buildings can reduce installation costs considerably by using the existing operating facilities for water purification and supply. Changwon city, Korea, has been using riverbank filtrate water for the indoor air-conditioning at its Daesan water treatment plant since 2006. In this method, the most important factor for determining the...
In the present paper we present an experimental analysis and a thermal and hydrodynamic modelling of a newly designed flat-plate solar collector characterized by its corrugated channel and by the high surface area directly in contact with the heat transport fluid. The thermal and hydrodynamic modelling of the collector has been performed by means of the Finite Element Method (FEM), validated with...
A numerical model for an anode-supported intermediate-temperature direct-internal-reforming planar solid oxide fuel cell (SOFC) was developed. In this model, the volume-averaging method is applied to the flow passages in the SOFC by assuming that a porous material is inserted in the passages as a current collector. This treatment reduces the computational time and cost by avoiding a full three-dimensional...
Transient three-dimensional heat transfer numerical simulations were conducted to investigate a hybrid PCM (phase change materials) based multi-fin heat sink. Numerical computation was conducted with different amounts of fins (0 fin, 3 fins and 6 fins), various heating power level (2 W, 3 W and 4 W), different orientation tests (vertical/horizontal/slanted), and charge and discharge modes. Calculating...
The viscous dissipation effect on the thermodynamic performance of the curved square microchannels in laminar flow is numerically investigated. The classical Navier–Stokes equations are adopted; aniline and ethylene glycol are selected as the working fluids. The results show that the heat transfer entropy generation number and frictional entropy generation number augment relatively under viscous dissipation...
This paper provides a comparative study of the performance of cross-flow and counter-flow M-cycle heat exchangers for dew point cooling. It is recognised that evaporative cooling systems offer a low energy alternative to conventional air conditioning units. Recently emerged dew point cooling, as the renovated evaporative cooling configuration, is claimed to have much higher cooling output over the...
A multidisciplinary approach for the design of geothermal power plants for water dominant resources is here proposed. The importance of a strategic approach is underlined, considering all the connections between the analysis of the geothermal potential of the reservoir (geophysical exploration and geochemical analysis) with the design of the plant based on thermodynamic and energy considerations,...
Oxy-fuel combustion is considered as one of promising options for carbon dioxide capture in future coal power plants. Currently models available in CFD codes fail to predict accurately the radiative heat transfer in oxy-fuel cases due to higher pressure of carbon dioxide and water vapor. This paper concerns numerical investigation applying three band formulations aiming an accurate prediction of radiative...
The research refers to the district heating (DH) system in Ljubljana, which includes 245km of highly diversified pipelines. The purpose of this study was to determine the effect of the soil thermal conductivity coefficient (λ s ) on the heat loss from pre-insulated pipes during operation. Pipeline geometry, material properties (particularly insulation and soil thermal conductivity) and time-dependent...
A possibility of simplification of the scattering phase function of a pulverized coal flame was analyzed in the paper. It was showed that the type of radiation scattering of a pulverized coal flame is between two limiting cases: isotropic and forward scattering. A comprehensive mathematical model of a tangentially fired furnace by pulverized coal was formed. Radiative heat transfer was modeled using...
Solar chimney power plants are a technology capable to generate electric energy through a wind turbine using the solar radiation as energy source; nevertheless, one of the objectives pursued since its invention is to achieve energy generation during day and night. Soil under the power plant plays an important role on the energy balance and heat transfer, due to its natural behavior as a heat storage...
The effects of hydrogen peroxide addition on the reaction pathway of premixed methane/air flames are numerically investigated using the PREMIX code with the GRI-Mech 3.0 chemical kinetic mechanisms and detailed transport properties. Hydrogen peroxide is used as the oxidizer substituent of air. Results show that the laminar burning velocity and adiabatic flame temperature of premixed methane–air flame...
The dynamic model of a novel household refrigerator with SSPCM (shape-stabilized phase change material) heat storage condenser presented in this paper were established and agreed well with the experiment. By simulation, the coefficient of performance is increased about 19% by a continuous heat transfer of condenser due to the latent heat storage of SSPCM, however the energy saving is 12% and offset...
The study of ways of converting ocean wave energy into a useful one and the improvement of the existing equipment are complex engineering problems and very important issues in today's society. In this paper, the onshore oscillating water column device, in a 10 m deep channel subjected to 1 m high incident wave and wave periods from 4 s to 15 s, is investigated. The numerical analyses are carried out...
In the geothermal energy utilization of a closed loop groundwater system of a GWHP (groundwater heat pump) and an ATES (aquifer thermal energy storage), thermal breakthrough is a very important aspect in the design of these systems. It can cause a gradual variation in the temperature of the pumping water and impact the efficiency of the GWHP. For pumping and injecting well groups, the influence of...
The cascade refrigeration system has been applied to heat pump water heaters to overcome the problems which arise from the high compression ratio at low ambient temperature. In this study, the performance of a cascade heat pump water heating system is investigated with a quasi-steady state analysis to find out the transient behavior of the system. The water-heating system consists of the cascade heat...
The objective of this study was to use both field data and a numerical simulation to examine the long-term performance and environmental effects of a large GSHP (ground source heat pump) system that heats and cools industrial greenhouses in a cold region. A large vertical GSHP system was installed in the city of Akabira in the north of Hokkaido, Japan to provide heating and cooling for 12 greenhouses...
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